Delay line



D. FALES lll Nov. 27, 1956 DELAY LINE Filed Nov. 3, 1955 INVENTOR flavidfiles, BY up and, 6.

ATTORNEY United States Patent DELAY LINE David Fales HI, Towson, Md., assignor to The Glen L. Martin Company, Middle River, Md., a corporation of Maryland Application November 3, 1955, Serial No. 544,768

7 Claims. (Cl. 33331) The present invention relates to a delay line of the concentric type wherein independent sections of the line are coaxially aligned arranged for sliding movement together and apart whereby the line possesses variable delay characteristics, and more particularly to a delay line of the type described wherein sliding movement of the line sections is effected without electrical contact.

There are already known arrangements for performing elongation and contracting of a delay line of the concentric type. In all of these arrangements, however, there exists the possibility of generating noise or of having erratic operation during elongation and contracting that could be of harm to some of the systems in which a delay line of this type is conventionally employed. It is accordingly an object of the present invention to provide a delay line of the type described wherein the elongating and contracting of the line is efiected in a fashion which will not produce erratic operation or generate noise and thus the systems in which the delay line is employed will not be subject to the resultant harmful effects.

It is a further object of the present invention to provide a delay line of the type described which functions Without any sliding metal to metal contacts which would have a tendency to generate noise and produce erratic operation that could in turn cause harmful effects in some of the systems in which the delay line would be employed.

Other and further objects of the present invention, as well as additional advantages, will become readily apparent from the following detailed discussion of the invention when taken in conjunction with the drawings, in which:

Figure 1 is a view in elevation of a delay line prepared according to the invention;

Figure 2 is a view in section taken along line 22 of Figure 1; and

Figure 3 is a view in section taken along the axis of the line.

Referring now to the drawings, there will be described a preferred form of the present invention. As will be evident, there is displayed in the figures of the drawing a coaxial transmission line comprised essentially of an outer annular conductor and a solid inner conductor 11, the two being maintained in concentric alignment by the use of spacers as is conventional in this art. The outer conductor 10 is cut on a bias or at an angle as indicated by its out surfaces 12 and 13. The outer conductor 10 is characterized by a plurality of drilled holes which are equally peripherally disposed about the cut faces 12 and 13. Each successive alternate hole is drilled to a larger diameter and fitted into these holes are insulating sleeves 15 having an internal diameter substantially equal to the diameter of the smaller set of holes drilled into the outer conductor 10. These insulating sleeves 15 are actually dielectric tubes and may be composed of polystyrene or other like material. Metal or conducting rods 16 are received in the drilled holes and also in the dielectric tubes 15. It will be noted at this point that each drilled hole containing a dielectric tube 15 in one part of conductor 2,772,401 Patented Nov. 27, 1956 10 is axially aligned with one of the smaller drilled holes on the other part of the outer conductor. The rods 16 are soldered into the smaller drilled holes of the outer conductor or in other words, those holes which do not have placed in them dielectric tubes 15. The steel rods 16 are left free in the dielectric tubes 15 and thus engage the tubes 15 for sliding movement. It will be apparent from the above description that the rods 16 can slide within the dielectric tubes 15 as the coaxial line is elongated and contracted. It is also apparent that the rods 16 are soldered alternately to both sides of the cut outer conductor 10.

The inner conductor 11 is likewise cut at the same angle as the outer conductor 10. As before, a plurality of holes are drilled into each cut face peripherally spaced. Each successive alternate hole on each cut face is drilled .to a slightly larger diameter for the purpose of receiving a dielectric tube 17. The internal diameter of the tube 17 is substantially equal to the diameter of the smaller drilled holes. By means of this construction, each drilled hole containing a dielectric tube 17 is axially aligned with a smaller drilled hole in the opposite cut face. Rods 18 are soldered into each smaller drilled hole at one end and their other ends are received in the dielectric tubes 17 in the larger drilled holes. The material result of this construction is that the rods 18 are free for sliding engagement with the dielectric tubes 17 as the inner conductor 11 is stretched and contracted.

For the purpose of elongating and contracting the line there is provided an insulated bracket 30 for anchoring one of the line sections and a rack 31 attached to the other line section and driven by a pinion 32. Crank 33 is provided as a convenient means for driving pinion 32. It will no doubt be appreciated that other arrangements can be equally successfully employed for the purpose of elongating and contracting the line and that what has been specifically described should be considered as merely illustrative of one mode of accomplishing this purpose.

The rods 16 and 18 are preferably stainless steel and it is proposed for a Vs coaxial line to use approximately 16 rods for the outer conductor 10 and approximately 8 rods for the inner conductor 11. The actual number of rods that will be used for any specific line will be largely determined by the desired match and the type of line. The amount of phase shift achieved with this construction has been found to be generally proportional to the frequency. The VSWR (Voltage Standing Wave Ratio) can be held to 1.3:1 or better over a very wide frequency band such as an octave.

Although the present invention has been shown and described with reference to a preferred embodiment, nevertheless, changes and modifications obvious to one skilled in the art are deemed to be within the spirit, scope and contemplation of the invention.

What is claimed is:

l. A device comprising a pair of sections each composed of an inner and an outer conductor, said sections being axially aligned and spaced apart, each of said outer conductors defining a bore, a dielectric sleeve received in one of the bores defined by said outer conductors, a rod received in said sleeve for relative sliding movement and fixed in the other bore, each of said inner conductors defining a bore, a second dielectric sleeve received in one of the bores defined by said inner conductors, and a rod received in said second sleeve for relative sliding movement and fixed in the other bore of said inner conductors.

2. A device as defined in claim 1 wherein the opposing faces of said sections are inclined.

3. A device as defined in claim 1 wherein the bores defined in said inner and outer conductors extend axially.

4. A device as defined in claim 3 wherein the bores defined by said outer conductors are axially aligned and said bores defined by said inner conductors are axially aligned.

5. A device as defined in claim 1 wherein each of said inner and outer conductors defines a plurality of peripherally spaced boress'a'id 'plur'alityaof bores defined by said outerconductors being arranged in pairs with a dielectric sleeve received in one of the bores of .each pair,v a rod of the bores of eachpair, and a rodreceived in eaehsaid second sleeve for relative sliding movement and fixed in the other bore of the pair.

6. A device as defined in claim 5 wherein the plurality of bores defined by said outer conductors are axially aligned and wherein the plurality of bores defined by said inner conductors are axially aligned.

7. A device as defined in claim 5 wherein the first mentioned dielectric sleeves are received in alternate bores defined by the outer conductors and wherein the second dielectric sleeves are received'in alternate bores defined by the inner conductors.

No references cited. 

